Dental curing light

ABSTRACT

An optical sensor for an instrument to form a closed-loop curing instrument that is configured to manage the quantity of delivered energy to a curable material, including a composite restoration for a tooth. The closed-loop curing instrument is configured to analyze a signal indicative of the light reflecting from the curable material, and to adjust light output based on the analysis.

TECHNICAL FIELD

The present disclosure relates to dental curing lights, and moreparticularly to controlled delivery of light from a dental curing light.

BACKGROUND

With the introduction and subsequent market penetration of light curedcomposite compounds used for Class 2 restorative dentistry, significantgains were made in the structural quality, natural appearance, andlongevity of restorative dental work. However, at the same time, a newcurve was thrown at the dentist. Unlike the older traditional amalgamfillings, once a composite filling was successfully placed and shaped,the dentist was still not finished. In an effort to completelypolymerize the compound and to try to assure a problem free placement,the dentist would cure the compound with an intense light of aprescribed wavelength. A majority of the early curing lights that wereused to achieve this function utilized a halogen based incandescent lampas the light source. The technology was simple and relatively affordablebut it was a bit “power hungry”, and produced a high degree of wasteheat, both at the lamp and at the tooth being treated. Designrefinements to optically filter the wavelengths of the energy that wereactually delivered to the tooth significantly reduced the unnecessaryheating of the tooth. This was a helpful refinement as the conventionalphoto activators used to induce cross-polymerization of most restorativecompounds only utilize a portion of the blue light spectrum. Byfiltering out much of the Green, Red, and Infra-Red portions of thelight being delivered to the tooth, advancements were made towardeliminating a majority of the unrequired wavelengths that result innothing more than “waste heat” at the tooth. Typical curing times for atooth restoration with light cured composites was in the range of 20 to60 seconds.

Then, in the mid to late 1990s, came the dawn of the blue highbrightness LED, and not too long thereafter, the rise of the blue LEDcuring wand. Blue LEDs that emitted light in the 450 to 485 nanometerwavelength range were well suited, spectrally at least, for the curingof dental composites. Power capabilities and pricing of the new blueLEDs were a limiting factor for several years—well into the newmillennia. However, it was not long until LED curing wands providing areliable 200-300 mW/cm2 (milliwatts per sq. centimeter) were technicallyviable and commercially available. This allowed introduction of smallhand-held battery operated curing lights that could perform 20-60 secondcomposite cure times similar to their older cord based halogenpredecessors.

Conventional LED curing wands have advanced significantly beyond thecapabilities of the initial blue LED curing wand. There are nowhand-held battery operated curing lights capable of producing in excessof 10 times their predecessor's power—many at 3,200 mW/cm2 or more, andsome now as high as 8,000 mW/cm2. This results in a curing light thatcan, in theory, cure a composite placement in a mere 1 to 3 seconds bydelivering the target amount of total optical energy (usually measuredin Joules) in less than one tenth the time. These advancements, however,are not without downsides.

Some conventional dental light wands operate with means for testing theoptical output, such as in the base of the charging stand. However,there is no feedback mechanism incorporated into such a dental lightwand, itself.

Conventional LED based curing lights have progressed to address severalconcerns over the past many years with respect to cordless operation,user ergonomics, digitally controlled exposure times and much higheroptical power availabilities. However, these improvements have donelittle to eliminate many of the causes or issues, such as uservariances, that often times prevent safe, repeatable, and reliablecompound cures. And, in some respects, the significantly higher powerlevels of recent curing lights have allowed more frequent overexposure,which may affect the ability to achieve enhanced safety and repeatableand reliable compound cures.

SUMMARY OF THE DESCRIPTION

An instrument for applying light energy to a light-curable target. Theinstrument may include a light source capable of outputting the lightenergy to the target, where the light source is controllable to varylight energy being output. The instrument may include a light sensor forsensing a light energy characteristic, and an optical feedback pathoperably coupled to the light sensor. The optical feedback path may bedisposed to channel light reflected back from the target to the lightsensor, where the light sensor is configured to sense a light energycharacteristic with respect to the light reflected back from the target.The instrument may further include a controller operably coupled to thelight sensor and the light source. The controller may be configured tovary, based on the light energy characteristic sensed by the lightsensor, an operating characteristic of the light source to adjust thelight energy being output from the light source.

In one embodiment, the optical sensor and related elements form aclosed-loop LED curing wand that manages the quantity of deliveredenergy to a composite restoration at the tooth with much greaterprecision than conventional curing instruments. The instrument accordingto one embodiment of the present disclosure does not control thequantity of delivered energy by measuring the amount of light energycreated in the LED based wand, but rather by measuring, in real time,the portion of that light that is actually hitting the targeted surfaceof the tooth restoration at any given moment and then managing theelectrical power applied to the LED source within the instrument todrive to desired levels of irradiance at the targeted tooth surface. Inso doing, both enhanced quality and enhanced safety of the light cureexposure may be achieved.

In one embodiment, a curing instrument for curing a light-curablematerial may include at least one of a light source, optical drivecircuitry, a controller, an optical feedback sensor, and a light sensor.The light source may be configured to generate light energy to cure thelight-curable material, and to provide an illumination beam of lightenergy to be delivered to the light-curable material. The optical drivecircuitry may be configured to provide a power signal to the lightsource to generate the light energy, where the optical drive circuitryis configured to vary one or more operating characteristics of the powersignal to vary the output of light energy from the light source. Thecontroller may be configured to control operation of the optical drivecircuitry to control generation of the light energy from the lightsource, and the optical feedback sensor may be arranged to collect lightreflected from the light-curable material. The optical feedback sensormay include a light input with an optical sense path directed to thelight-curable material, where the optical sense path of the light inputis surrounded by the illumination beam generated from the light source.Optionally, the light input may correspond to a distal end of afiber-optic element that is constructed according to a side-fireconfiguration such that the optical sense path is substantially 90°relative to a central axis of the fiber-optic. The distal end may bepositioned relative to the illumination beam such that substantialshadowing of the illumination beam is avoided.

The light sensor may be optically coupled to the light input of theoptical feedback sensor, and may be configured to generate an opticalsensor feedback signal based on the light collected by the light input.Based on the optical sensor feedback signal, the controller of thecuring instrument may direct the optical drive circuitry to vary outputof light energy from the light source.

A method of manufacture according to one embodiment may include emittinglight from the light input of the optical feedback sensor and emittinglight from the light source. The method may include comparing the outputbeam from the light input to the illumination beam of the light sourcein order to facilitate aligning the output beam with the illuminationbeam (e.g. coaxial in aligning the output and illumination beams). Inembodiments in which the light input is a side fire construction, theoptical feedback sensor may be rotated and moved laterally into positionsuch that the output beam is coaxially aligned the illumination beam.After coaxial alignment is achieved, at least a portion of the opticalfeedback sensor may be affixed to a stationary part of the curinginstrument, such as a lens coupled to the light source, to substantiallyprevent movement of the light input relative to the light source.

In one embodiment, a method of operating a curing light to cure alight-curable material may include at least one of the following steps:generating light energy from a light source, directing that light energytoward a target surface of the light-curable material, generating anoptical sensor feedback signal based on sensed light reflected from thetarget surface, and adjusting output of the light energy from the lightsource based on the optical sensor feedback signal.

The method of operation may further include one or more of iterativelycalculating the amount of light energy applied to the target surface,determining whether the amount of light energy is consistent with acuring operation profile, and determining whether a total amount oflight energy directed to the target surface is consistent with aprescribed amount of light energy for curing the light-curable material.

One or more embodiments described herein may achieve a real andeffective construction that possibly avoids the potentially dangerousand potentially painful chance of overexposure to light energy, whichmay lead to thermal tissue damage. In this way, a more powerful curinginstrument may be used while avoiding the conventional approach ofdoubling or tripling exposures. The closed loop LED curing lightapproach may eliminate the wasted time and at the same time potentiallyeliminate possibly adverse effects associated high power curing lights.

These and other objects, advantages, and features of the disclosure willbe more fully understood and appreciated by reference to the descriptionof the current embodiment and the drawings.

Before the embodiments of the invention are explained in detail, it isto be understood that the invention is not limited to the details ofoperation or to the details of construction and the arrangement of thecomponents set forth in the following description or illustrated in thedrawings. The invention may be implemented in various other embodimentsand of being practiced or being carried out in alternative ways notexpressly disclosed herein. Also, it is to be understood that thephraseology and terminology used herein are for the purpose ofdescription and should not be regarded as limiting. The use of“including” and “comprising” and variations thereof is meant toencompass the items listed thereafter and equivalents thereof as well asadditional items and equivalents thereof. Further, enumeration may beused in the description of various embodiments. Unless otherwiseexpressly stated, the use of enumeration should not be construed aslimiting the invention to any specific order or number of components.Nor should the use of enumeration be construed as excluding from thescope of the invention any additional steps or components that might becombined with or into the enumerated steps or components.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 depicts a curing instrument according to one embodiment.

FIG. 2 shows a representative view of the dental curing instrument ofFIG. 1.

FIG. 3 shows a partially sectioned and exposed view of a lightapplication member of the dental curing instrument of FIG. 1

FIG. 4 is a method of operating a curing instrument according to oneembodiment.

FIG. 5 is a method of operating a curing instrument according to oneembodiment.

FIG. 6 is a method of operating a curing instrument according to oneembodiment.

DETAILED DESCRIPTION

A curing instrument for providing light to a composite material during acure is shown in FIGS. 1-2 and generally designated 100. The curinginstrument 100 may be used to cure a light activated composite material,such as by polymerizing monomers into durable polymers. The curinginstrument 100 may be a standalone device, such as a portable handheldwand having a battery power source, or a component of a curing systemhaving a base unit to which the curing instrument 100 is tethered andreceives power therefrom. A variety of fields may benefit from thecuring instrument 100, including, for example, the dental and medicalfields. For purposes of disclosure, the curing instrument 100 isdescribed as being a dental curing instrument for use in connection withcuring a composite material having photo initiator, which absorbs lightof a particular wavelength and causes polymerization of the monomersincluded in the composite material into polymers. It should beunderstood, however, that the present disclosure is not limited to thecuring instrument being a dental curing instrument or limited to usewith dental composite material—any curing application may benefit fromthe curing instrument, and any type of photo curable material may beused in conjunction with the curing instrument, including transparent,translucent and opaque curable materials.

In the illustrated embodiment of FIGS. 1-2, the curing instrument 100may include a light application member 20, an operator interface 12 andan operator feedback element 14. In use, an operator may activate thecuring instrument 100 via the operator interface 12 (e.g. a start button“S”) to initiate a curing operation of a composite material (not shown).After activation, the curing instrument 100 may generate and emit lightthrough a light passage of the application member 20. The operator mayposition the light application member 20 such that the light passagedirects light toward the composite material in order to effect a curethereof.

The operator interface 12 may enable operator selection of one or moresettings or modes of the curing instrument 100, as described herein,such as by selecting a input (e.g., a mode button “M”). For example, theoperator interface 12 may enable operator selection of one or more of adesired curing or exposure time, a desired power output, an operating ordelivery mode, and an ON/OFF trigger. The one or more settings or modeselector by the operator may be identified via the operator feedbackelement 14, which may include one or more LEDs or a display, or acombination thereof. With the operator feedback element 14, the operatormay be informed or made aware of operational settings or modes of thecuring instrument 100. In one embodiment, the operator feedback element14 may include a display in the form of an LCD or LED display.

The curing instrument 100 may be configured to control emission of lightfrom a light source based on feedback from an optical sensor. In somecases, output from the light source may be tightly managed to accountfor variations in battery charge, LED life, and other related systemcomponent variations, or a combination thereof, in an effort to achieveconsistent generation of light or power output from the light source.However, even with such management, deviations may occur in delivery ofa desired light level or power output at the intended target (e.g., thecomposite material). Many factors “external” to the curing instrument100 may affect light delivery, including a variety of operator errorssuch as contamination of a tip or light output of the curing instrument100, or distance and angular variations between the light output of thecuring instrument 100 and the targeted surface (e.g., a tooth surface)during the cure. These and other external factors may significantlyimpact how much optical energy actually makes it to the intended ortargeted surface. The curing instrument 100 may be configured to utilizeoptical feedback to adjust light output in order to substantially reduceor eliminate the effects of external error sources, which can often bethe principal factor or factors in how much optical energy makes it tothe targeted surface.

The curing instrument 100 according to one embodiment may sense one ormore characteristics indicative of the amount of light actually makingit to the targeted surface, which includes the composite material, suchas a compound restoration that is targeted for curing. Based on the oneor more parameters, the curing instrument 100 may “throttle” the lightsource output, either up or down, to achieve a target irradiance power(mW/cm2) and total energy (Joules/cm2) delivered to the targetedsurface.

In other words, the curing instrument 100 may be configured to controlan amount of total optical energy applied (Joules) to the intendedtarget, and in so doing, the rate of power applied to the target(mW/cm2) during the exposure time may be controlled to avoid exceeding atarget level of optical energy. Control over optical energy output basedon optical feedback can be achieved in a variety ways. For purposes ofdisclosure, the present disclosure includes several embodiments thatimplement such control-based delivery of light to a curable material.However, it should be understood that the present disclosure is notlimited to the specific constructions and embodiments described herein,and that essentially any controlled curing instrument is contemplated.

In the illustrated embodiment of FIG. 2, the curing instrument 100 mayinclude a controller 10 (e.g., a low end embedded controller), opticaldrive circuitry 22, a light source 24, optical feedback circuitry 26,and an optical feedback sensor 28. The optical drive circuitry 22 maycontrol the supply of power to the light source 24 to generate lightthat may be transmitted via the light application member 20 to a targetsurface. For instance, the optical drive circuitry 22 may includecontrolled drive circuitry that receives power from a power source(e.g., a battery of the curing instrument 100), and provides that poweras a power signal to the light source 24 according to one or moreoperating characteristics, such as a voltage magnitude or currentmagnitude, or both. In response to receipt of power, the light source 24may generate light that can be directed to a target surface for thecuring operation. The light source 24 in the illustrated embodiment isprimarily an Ultra-Violet (UV) light source, such as a UV light emittingdiode (LED), but may be configured differently, including beingconfigured to primarily output infrared light. It should further beunderstood that the light source 24 of the illustratedembodiment—although primarily one type of light source (e.g., UV)—alsomay emit light of wavelengths different from those of the primary lighttype. For instance, the primary light output from a UV LED is UV light,but the UV LED may also emit light in the visible spectrum or infraredspectrum, or both, along with the UV light.

The controller 10 of the curing instrument 100 in one embodiment mayinclude an algorithmic computational solution element or controllermodule, such as a shared computational module incorporated into thecontroller 10, forming an embedded control system that controls lightoutput and potentially additional instrument functionality. Optionally,this module may be separate from the controller 10 and incorporated intoanother hardware module that along with the controller 10 forms at leastpart of a control system for the curing instrument 100.

Control over generation of light from the light source 24, as mentionedherein, may be conducted through the optical drive circuitry 22, whichis also referred to as an LED power control element but is not solimited. In the illustrated embodiment, the controller 10 may be coupledto and control operation of the optical drive circuitry 22. Thecontrolled level of the operating characteristic or operatingcharacteristics of the optical drive circuitry 22 may be governed atleast in part by the controller 10 to affect the power signal provide tothe light source and to affect light output thereof. For example, thecontroller 10 may provide a control signal or control information to theoptical drive circuitry 22 to provide power to the light source 24according to a target operating characteristic. The control signal orcontrol information provided from the controller 10 may be dynamic suchthat, during a curing operation, the control signal or controlinformation may vary to effect a change in the target operatingcharacteristic. The optical drive circuitry 22, in one embodiment, mayutilize feedback circuitry to achieve the target operatingcharacteristic. For instance, the optical drive circuitry 22 may includea current sensor that senses current supplied to the light source 24,and based on the sensed current, the optical drive circuitry 22 mayadjust operation to vary the supply current to more closely align with atarget supply current. Additionally or alternatively, the controller 10may direct operation of the optical drive circuitry 22 based on sensedinformation related to operation of the optical drive circuitry 22 insupplying power to the light source 24, including, for example,adjusting one or more target operating characteristics, such as dutycycle, based on a deviation between a target current and a sensedoperating current.

The optical drive circuitry 22 may include circuitry that turns ON/OFFthe light source 24, and that manages the power output during use. Theoptical drive circuitry 22 may receive input from the controller 10 tocontrol the output of the light source 24. The optical drive circuitry22 may include the capability of managing output power of the lightsource 24 with more resolution that merely turning ON or OFF orselecting one of two or three preset power levels. For instance, theoptical drive circuit 22 may control one or more operatingcharacteristics, including, for example, controlling duty cycle of powerapplied to the light source 24 to control the amount of output power. Asanother example, the optical drive circuitry 22 may control theamplitude or the rail voltage, or both, of power applied to the lightsource 24 to affect and control output power. In some circumstances, theoptical drive circuitry 22 may be controlled by the controller 10 toachieve “ramping” exposure profiles, or exposure profiles or operatingprofiles that change over the course of the curing operation rather thana profile configured to supply a substantially constant amount of lightenergy to a target surface. For instance, the curing instrument 100 mayvary an output level of the light source 24 to achieve controlled supplyof light energy to a target surface—with adaptive exposure profiles, atarget output level of the light source 24 may be shifted or varied overthe course of the curing operation while the controller 10 controlssupply of power to the light source 24 according to the target outputlevel for a given time of the curing profile in the curing operation. Asan example, the curing instrument 100 may supply a greater amount oflight energy to a target surface for a beginning period of the curingoperation, and supply a lesser amount of light energy during laterperiod of the curing operation.

The controller 10 of the curing instrument 100 may control the opticaldrive circuitry 22 based on feedback obtained from an optical feedbacksensor 28. Such optical feedback-based control may be implemented inconjunction with any of the control methodologies described herein,including, for example, controlling one or more operatingcharacteristics based on feedback from the optical feedback sensor 28 toachieve a target optical output. In the illustrated embodiment of FIG.2, the curing instrument 100 may include an optical feedback sensor 28configured to sense light reflecting from the target surface, to whichlight from the light source 24 is directed, and including an opticalfeedback path configured to channel light or a characteristic of lightto optical feedback circuitry 26. Based on optical feedback from theoptical feedback sensor 28, the optical feedback circuitry 26 maygenerate an optical sensor feedback signal indicative of the sensedlight and provide the optical sensor feedback signal to the controller10. By analyzing the optical sensor feedback signal, the controller 10may dynamically vary the control signal or control instructions providedto the optical drive circuitry 22, thereby dynamically adjusting one ormore operating characteristics of the optical drive circuitry 22 andoutput from the light source 24 based on sensed light reflected from thetarget surface. Additionally, or alternatively, the controller 10 maydetermine one or more timing aspects related to delivery of light basedon the optical sensor feedback signal, and dynamically calculate aduration for applying light to the targeted surface. For instance, basedon the optical sensor feedback signal, the controller 10 may determinean amount of light energy delivered to the target surface or a givenamount of time, and instruct or command the optical drive circuitry 22to discontinue delivering light energy in response to the amount ofdelivered light energy reaching or exceeding a threshold.

The curing instrument 100 according to the illustrated embodiment mayinclude a light sensor element in the optical feedback circuitry 26 thatis receives light or a characteristic thereof via the optical feedbackpath of the optical feedback sensor 28. The light sensor element of thecuring instrument 100 may be located so as to be systematicallyconnected to the controller 10 so that output of light from the lightsource 24 may be controlled based on sensed light. The light sensorelement of the optical feedback circuitry 26 may be a photodiode that issensitized to one or more wavelengths of light, such as the spectrum oflight corresponding to UV radiation. It should be understood that anytype of light sensor element may be incorporated the optical feedbackcircuit 26, and that the light sensor element may be sensitive to morethan one spectrum of light. The optical sensor feedback signal receivedby the controller 10 may be an analog signal from the optical feedbackcircuitry 26. The controller 10 may be configured to convert the analogsignal to digital information for further processing as describedherein. Additionally, or alternatively, the optical sensor feedbacksignal provided by the optical feedback circuitry 26 may be a digitalsignal representative of information or data relating to reflected lightsensed by the light sensor element of the optical feedback circuitry 26.

As an alternative or in addition to the light sensor element, the curinginstrument 100 may utilize a light and/or heat sensor that is located ator substantially near the targeted surface of the tooth. Thisconfiguration may offer enhanced accuracy for controlled delivery ofenergy to the tooth. This configuration may also be usable with lesscalibration.

In one embodiment of the curing instrument 100, the optical feedbacksensor 28 may serve to preferentially collect some portion of the lightreflected off from the surface of the intended target area of the area(e.g., the composite material) being treated, and may also serve todeliver this light to the light sensor element of the optical feedbackcircuitry 26 for quantification. The optical feedback sensor 28 may bepositioned relative to the light application member 20 such that a lightinput 58 of the optical feedback sensor 28 is disposed to collect lightreflected from the target surface. The optical feedback sensor 28according one embodiment may be an optical fiber with the light input 58being formed at a distal end of the optical fiber. The light input 58may be surface treated, such as by polishing, so that the light input 58is configured to collect reflected light, as described herein. In oneembodiment, the optical fiber may be configured such that a distal endcorresponding to the light input 58 is constructed as a side-firing tip.With this construction, the optical fiber may collect light at an angledifferent from a central axis of the optical fiber, including, forexample, light directed substantially perpendicular with respect to acentral axis of the optical fiber. The distal end of the optical fiberin a side fire configuration may be treated such that a surface of thedistal end is angled (e.g., about 42 deg.) relative to the central axisof the optical fiber. It should be understood that the optical feedbackcircuit 28 may be arranged to collect light at different angles,including, for example, between 20 and 160 deg. relative to the centralaxis of the optical fiber.

In the illustrated embodiment, the light sensor 28 may not be configuredfor the purpose of sensing LED output from the light source 24, butrather to sense the light reflected back from the targeted surface. Thislight sensor arrangement may achieve an optical connection between theoptical feedback circuitry 26 and the “target” surface via the opticalpath element or light sensor 28. Such an optical path may beaccomplished by an isolated, dedicated optical fiber, or by otherblended optical arrangements, so as to enable the optical signalreceived by the light sensor of the optical feedback circuitry tolargely, or at least in part, include the light reflected off of thetargeted surface. The optical sensor feedback signal, generated by theoptical feedback circuitry 26 and based on the light provided via theoptical path of the light sensor 28, may then be processed by thecontroller 10 to eliminate or greatly reduce known and derived sensoryerror sources as well as to compensate for optical factors impacting theoptical sensor feedback signal and to thereby compute in real-time a“delivered” energy level (in mW/cm2) at the actual targeted surface. Asexplained herein, the computation of actual irradiance level at thetargeted surface may form a basis of operation according to one or moremethods or modes of operation.

In one embodiment, the controller 10 may be configured to control theoutput of light from the light source 24 based on the optical sensorfeedback signal according to a first operational mode in which thereal-time “delivered” energy value may be digitally integrated duringthe time of the exposure to compute the total Joules of energy deliveredto the targeted surface up to that point. As the delivered energyreaches the desired level (for example, 48 Joules for a dark shaderestoration) the controller 10 of the curing instrument 100 mayautomatically turn off the light source 24 and notify the operator thatthe exposure has been completed. In a second operational mode, thecuring instrument 100 may use the computed irradiance at the targetedsurface (e.g., the tooth or composite material surface) to create an“error value” in real time that represents the over or under exposure atthe targeted surface for that moment in time with respect to a targetirradiance level initially set or expected by the operator of the curinginstrument 100. This error signal may be used as a basis for throttlingthe light source 24 up or down to substantially ensure that the targetsurface is receiving a desired amount of mW/cm2 of irradiance at anygiven moment of the curing process or operation. This second mode mayalso help to ensure that overly intense irradiation levels are avoidedinstead of merely shortening the total exposure time.

A partially exposed and partial sectional view of the light applicationmember 20 according to one embodiment of the curing light 100 isdepicted in the illustrated embodiment of FIG. 3. The light applicationmember 20 may include the optical drive circuitry 22, the light source24, the optical feedback circuitry 26, and the optical feedback sensor28. The light application number 20 may also include a hemisphericallens 50 mounted to the light source 26, a plano-convex lens 52configured to direct light energy from the light source 24 to a targetsurface and a reflector ring 56 configured to direct light toward theplano-convex lens 52. The light application member 20 may also include abezel or outer retainer ring 54 constructed to maintain the position ofthe plano-convex lens 52, the light source 24, and the reflector ring56. It should be understood that one or more of the lens types and lensconstruction of the light application member 20, as well as the physicalarrangement or use of one or more components including the bezel 54 andthe reflector ring 56, may be different and may vary from application toapplication.

In the illustrated embodiment, the light source 24 and the light input58 of the optical feedback sensor 28 may be disposed such that anoptical path 62 of the light input 58 is within an optical path 64 ofthe light source 24. For instance, the optical path 62 of the lightinput 58 may be coaxial and narrower with respect to the optical path ofthe light source 24. In operation, the optical path 62 of the lightinput 58 may be arranged to collect light to sense as a basis forcontrolling operation of the curing instrument 100, whereas the opticalpath 64 of the light source 24 may be arranged to direct light from thelight source 24 to a target surface. The optical path 62 may beconsidered part of the optical feedback path provided by the opticalfeedback sensor 28 to channel light to the light sensor of the opticalfeedback circuitry 26.

At manufacture, as discussed herein, the optical feedback sensor 28 maybe energized from a light source to emit light from the light input 58,thereby facilitating alignment of the optical path 62 of the light input58 with respect to the optical path 64 of the light source 24. Forinstance, by emitting one type of light from the light input 58, acomparison can be made against another type of light emitted from thelight source 24 in order to align the optical path 62 of the light input58 with respect to the optical path 64 of the light source 24. Afteralignment has been conducted, the optical feedback sensor 28 may besecured in place, such as by utilizing optical glue to affix a portionof the optical feedback sensor 28 to a portion of the light applicationnumber 20, to substantially prevent linear and rotational movement ofthe light input 58 of the optical feedback sensor 28.

By aligning the optical path 62 of the light input 58 with respect tothe optical path 64 of the light source 24, the curing light 100 mayachieve enhanced accuracy in the optical sensor feedback signal used bythe controller 10 to provide the closed loop control of the curing light100.

In the illustrated embodiment of FIG. 3, the light input 58 of theoptical feedback sensor 28 may be disposed to capture the lightreflected from the target surface, and such that the optical path 62 isaligned with and coaxial about a central axis 60 of the optical path 64of the illuminating beam of the light source 24. In this way, theoptical path 62 of the light input 58 may be considered a sensingoptical path, and the optical path 64 of the light source 24 may beconsidered an illuminating optical path. Alignment of the illuminatingand sensing optical path, such as coaxial alignment of these opticalpaths, may assure that the sensed zone of the target surface does notsubstantially migrate within the illuminated zone of the target surfaceas a function of distance from the source. In other words, if the pairof illuminated and sensed optical paths (or “beams”) 64, 62 havedifferent trajectories, the sensed zone of the sensing optical path 62may move substantially outside the illuminated zone of the targetsurface as the distance between the light application member 20 and thetarget surface increases. By aligning the sensing beam or “viewed area”of the target surface with the illumination beam, the illumination beamcan be convergent, divergent, or even highly collimated, or acombination thereof, without significantly affecting the feedback signalgenerated from the sensing beam.

Alignment of the illumination optical path 64 and the sensing opticalpath 64, including coaxial alignment, with respect to the target surfacemay help to assure that the optical sensor feedback signal is stableover varying distances. Distance is one of the principal variablesintroduced into a curing operation during handheld operator use.Stabilization of the optical sensor feedback signal over varyingdistances may enable the curing light 100 to compensate for operatorintroduced variations in distance, enabling more accurate delivery oflight during a curing operation.

Alignment of the optical path 62 of the light input 58 and the opticalpath 64 of the light source 24 may be achieved in a variety of ways, asdiscussed herein. In one embodiment, this alignment may be achieved byutilizing a beam splitter technique, including, for example, directinglight from the light source through a 45 deg. beam splitter so that partof this light is directed to a first side and the other part of thislight is directed to the target surface. Light reflected from the targetsurface may interface with the beam splitter such that some of thereflected light passes through toward the light source, and the otherpart of the reflected light is directed to a second side, which isopposite the first side. A sensor may be optically coupled to the secondside to detect a characteristic of the reflected light, which can beused as a basis for closed loop feedback control of the light source.

In the illustrated embodiment, the optical path 62 of the light input 58may be aligned with the optical path of the light source 24 throughmanagement of the physical size of the light input 58 and the opticalfeedback sensor 28, enabling collection of light via the optical path 62where the light input 58 is substantially small relative to anintersecting surface area of the optical path 64 or the illuminationbeam. In other words, the optical feedback sensor 28, including thelight input 58, may be constructed and positioned such that the amountof area of the optical path 64 that is covered by the optical feedbacksensor 28 is small in relation to the total area of the optical path 64in the same plane as the covered area. In this way, a shadowing effectof the optical feedback sensor 28 may be reduced, or put differently,the optical feedback sensor 28 may be constructed and positioned so thatit does not provide a measurable or significant impact on the uniformityor intensity of the illumination beam on the target surface. As anexample, the optical feedback sensor 28, as described herein, may be a“side-fire” type of optical fiber in which the light input 58corresponds to a distal end that is terminated and polished to achieve anear right angle distribution cone or reception cone, or both, at thelight input 58. A small optical fiber may be utilized, e.g., withinrange of 0.005″ to 0.020″ in diameter, such as 0.010″ in diameter, witha side-fire optical termination (as provided, for example, by PolymicroFibers), and placed into the illumination path close to the light source24 with a coaxial alignment to avoid significant shadowing. Thisconstruction may achieve a useful alignment of the optical path 62 andoptical path 64 in a cost-effective manner without substantiallyadversely affecting curing of the target surface with the light source24.

The curing instrument 100 according to one embodiment may be a highpower (>2000 mW/cm2) LED based dental curing wand. More specifically,the curing instrument 100 may be capable of varying an optical outputlevel of the light source 24, such as a high power LED, to cure a dentalcomposite material according to manufacturer specifications for thematerial. The curing instrument 100 may form part of an optical deliverysystem that according to one embodiment may be capable of sustaining atleast 2000 mW/cm2 at a target distance of 2 cm to 5 cm from the a tip ofthe light application number 20, and may be configured such that aprofile of irradiance across the beam generated by the tip issubstantially homogeneous within 20% of the average power across thetip. It should be understood that the present disclosure is not limitedto these features and that alternative instrument or wand configurationsare contemplated.

A curing instrument 100 according to one embodiment with all or some ofthe features described above may achieve closed-loop control of lightoutput to a target surface. Alternatively or additionally as anothermode of operation, the curing instrument 100 may achieve open loopcontrol of light output to the target surface. With the ability to senseoptical output as feedback, and to use the feedback to compute, track,and compensate for actual optical energy being delivered to the surfaceof the tooth, the curing instrument 100 may significantly enhanceclinical performance and provide enhanced safety in curing dentalrestorative compounds. In so doing, the curing instrument 100 may helpto substantially eliminate a great number of variables impactingexposure level at the targeted surface and the subsequentpost-procedural problems that sometimes occur with either under exposure(e.g., insufficient cure of compound) or over exposure, which maypotentially cause damage to live tissue from over-heating.

A curing instrument 100 according to one embodiment may be configuredwith a quality optical design by implementing controlled manufacturingprocesses to produce an instrument that demonstrates a substantiallyhomogeneous field of light across the tip of the instrument that isconsistent from use to use, even if the light source 24, itself, isinclined to exhibit a slight, but continuous, decay in its output levelover its “life”. It is noted that LEDs often times do not “burn out” ina catastrophic fashion as do their incandescent counterparts, but rathertend to slowly decrease in intensity over their life. LED lifetime canbe expressed as the number of hours before they reach either 50% or 70%of original intensity, depending on the LED “life” standard that isbeing used. The controller 10 of the curing instrument 100 may adjustoutput intensity of the light source 24 based on the optical sensorfeedback signal to counteract degradation of the light source 24 overits lifetime. The controller 10 may also conduct diagnostic analysisbased on the optical sensor feedback signal, such as determining whetherthe light source 24 is operating according to one or more operationalparameters sufficient for conducting a cure operation. In this way, thecontroller 10 of the curing instrument 100 may conduct built indiagnostics (BIT). Additionally, or alternatively, the BIT conducted bythe controller 10 may include analysis of battery or power sourcestability or sufficiency or both, and determining whether contaminationis present on a lens or tip through which light is emitted from thelight application member 20.

After light from the light source 24 reaches the tip of the instrument,many additional variables can, and sometimes do, impact the effectivedelivery of those photons onto the intended surface. In cases of handheld use by an operator, probably the most significant of thesevariables is the operator's accuracy (or variance) with respect toplacement of the curing instrument 100 during the time of the exposureor the curing operation. Depending on various factors, such as theoptical design of the tip of the light applicator member 20, itseffective numerical aperture, and the geometry of tip diameter vs.intended working distance, a variation of better than 5 to 1 can beexperienced in light attenuation during hand held curing operations. Asan example, clinically relevant irradiance has been demonstrated to dropoff significantly in some cases due to a change in target distance from2 mm to 8 mm. Furthermore, additional variation as high as 2 to 1 mayoccur from angular variation between the axis of the tip surface and thenormal of the target surface being treated. The curing instrument 100according to one embodiment may be configured to substantially accountfor this variability by utilizing closed loop feedback based on sensedlight reflected from the target surface, thereby enabling control overthe irradiance.

It should be understood that the curing instrument 100 according to oneembodiment may implement closed loop control of light output based on asensed parameter or characteristic of light reflecting from the targetsurface, which itself may be indicative of the light energy at orreaching the target. In addition to basing control on the light sensedat the target, the instrument may internally sense internal light outputfrom the light source 24 of the curing instrument 100. Internallysensing the light output, alone without determining the amount of lightexternally applied to the target, may allow the curing instrument 100 tocompensate for aging or variations in the light source or lamp, butgenerally does not account for variables that may exist between thesource generation of the curing instrument 100 and the intended finaltarget destination of the light. Operator variations from use to use maybe compensated for by sensing a parameter indicative of the lightactually reaching the target.

The acceptance and utilization of composites for dental restoration hasgrown tremendously over the last couple of decades, including use ofcomposites on anterior teeth. Use of anterior tooth composites has givenrise to composites of different shades to match the same color of thenatural tooth to which the composite is being applied. The differentshade offerings, in many cases, call for different amounts of targetlight energy to complete a cure. Darker shades often cause much moreinternal attenuation of light as it is scattered about and transmittedthrough the composite material. This often results in increased targetenergy to cure the darker shades. As an example, a popular line ofrestorative compound offered by Dentsply cures at about an energy of 6Joules/cm² for lighter shades, but cures at 48 Joules/cm² for darkershades. This is an eight-to-one variation in prescribed energy deliveryand as such represents an additional 8 fold increase in the total rangeof appropriate energy levels that may now be prescribed to achieve atarget cure for various composite materials.

The curing instrument 100 according to one embodiment may be configuredto cure a restorative compound by controlling light output during thecure cycle to achieve a target output, possibly specific to the curablematerial or restorative compound being used. For instance, the operatormay utilize the operator interface 12 to select a target cure settingfor a curing operation that is prescribed by a manufacturer of thecurable material being used. In this way, the amount of light energyapplied during a curing operation may be selectively chosen based thematerial being used rather than “over-curing” the curable material by afactor of two or three to eliminate a potential under-cure due todistance, angle, or other external variation factors. If curingintensity levels are considered low (e.g., 200 to 300 mW/cm2),intentional over-curing a curable material by a factor of two or threeto eliminate a potential under-cure due to distance, angle, or otherexternal variation factors is often not considered to be an issue.However, with use of curable materials that prescribe higher cureenergies, and therefore a higher energy curing instrument (e.g., aninstrument that produces at least 1200 mW/cm2 and possibly up to 3000mW/cm2 or more), intentional over-curing can result in application ofenergy that is an order of magnitude greater than that of directsunlight (e.g., 100 mW/cm²). The curing instrument in the illustratedembodiment of FIG. 2 may utilize optical feedback based on lightreflected from the target surface to control the delivery of lightenergy, thereby substantially avoiding significant over-curing andintentional over-curing procedures that generate light energies two tothree times the prescribed amount.

A method of operation of the curing instrument or curing systemaccording to one embodiment is depicted in the illustrated embodiment ofFIG. 4, and generally designated 200. The method 200 may be implementedas a control module in the controller 10 using feedback based on one ormore parameters or characteristics, such as reflected light from thetarget surface, and one or more sense characteristics of the curinginstrument 100, itself. In the illustrated embodiment, the method 200may include initiating a cure operation and resetting an accumulator orintegrator that tracks an amount of light energy delivered to a targetsurface. Steps 210 and 212. The controller 10 may then instruct theoptical drive circuitry 22 to power the light source 24 according to aninitial setting, such as a preselected source power level, therebystarting application of light to the targeted surface. Step 214. Thereal-time “delivered” energy value may be digitally integrated duringthe time of the exposure to computationally represent the total Joulesof energy delivered to the targeted surface up to a given point in time.Steps 216, 218. As the delivered energy reaches the desired level (forexample, 48 Joules for a dark shade) the controller 10 may automaticallyturn off the light source 24 and notify the user that the exposure hasbeen completed. Steps 220, 222, 224. In this way, the curing instrument100 may vary the exposure time to compensate for factors affectingdelivery of light energy to the target surface, such as distance orangular variations present during each use.

Another method of operating the curing instrument according to oneembodiment is depicted in the illustrated embodiment of FIG. 5, andgenerally designated 300. The method 300 may be implemented by acontroller 10 similar to the method 200. In the illustrated embodiment,the method 300 may include initiating a cure operation and initializingor resetting an accumulator or integrator that tracks an amount of lightenergy delivered to a target surface. Steps 310 and 312. Initiation of acuring operation may start in response to activation of a user input(e.g., a button) of the operator input 12. The controller 10 may theninstruct the optical drive circuitry 22 to power the light source 24according to an initial setting, such as a preselected source powerlevel, thereby starting application of light to the targeted surface.Step 314. The method 300 may further include computing irradiance at thetargeted surface to generate an error value in real-time that representsthe over or under exposure at the targeted surface for that moment intime with respect to a target irradiance level initially set or expectedby the operator. Steps 318, 320.

This error signal may then be used as a basis for adjusting the opticaldrive circuitry 22 so as to either increase or reduce output from thelight source 24 by a calculated value and thereby assure that energylosses between the light source 24 and the target surface arecompensated and that the target surface is receiving the target numberof mW/cm2 of irradiance at any given moment of the curing process. Steps322, 324, 326. As an example, at step 322, the method 300 may determinewhether the amount of irradiance delivered (I_(delivered)) is greater orless than a calculated amount of expected irradiance, which maycorrespond to the desired or expected amount of irradiance (I_(desired))for a given time. As another example, the method 300 may determinewhether the amount of energy delivered (I_(delivered)) is greater orless than a calculated amount of expected energy, which may correspondto the desired or expected amount of energy (I_(desired)) for a giventime period, or correspond to a fraction of the total prescribed amountof energy for the curing operation for the period of time since thecuring operation was initiated. The method 300 may facilitatesubstantial avoidance of overly intense irradiation levels instead ofshortening the total exposure time.

The method 300 of the illustrated embodiment may after a predeterminedamount of time, such as 0.01 s, determine, based on the optical sensorfeedback signal, whether the total amount of energy delivered to thetarget surface meets or exceeds a threshold corresponding to aprescribed amount of light energy for a curing operation. Steps 328,330, 332. If the calculated amount of total energy satisfies thiscondition, the curing operation may be terminated. Steps 332, 334. Ifthe condition is not met, the curing operation may continue such thatthe calculated amount of energy is determined iteratively until thecalculated amount of total energy satisfies the condition. Steps 332,316.

The curing instrument 100 according to one embodiment may provide aconstruction that substantially ensures curable materials, such ascomposite dental materials, receive sufficient energy to properly curethe curable material without relying on a conventional and much lessaccurate approach of simply doubling or tripling a calculated exposuretime. In this way, a substantially effective energy deliverance to thetarget surface may be achieved. It should be understood that thetechniques and embodiments described herein may be extended tonon-dental applications such as industrial manufacturing where preciselight cure of adhesives or similar composite fills are utilized.

Optionally, the curing instrument 100 may be configured to least one ofprevent operation or alert the operator of issues related to improperalignment or an insufficient capability to deliver energy, such as incase a curing operation appears, based on the optical sensor feedbacksignal, to be insufficient to properly cure the curable material. As anexample, if the curing instrument 100 is improperly angled, possibly duein part to an improperly trained operator, the controller 10 may detectthat the curing operation is insufficient to cure the target material,and alert the operator accordingly, or discontinue operation, or both.

A method of the curing instrument or curing system according to oneembodiment is depicted in the illustrated embodiment of FIG. 6, andgenerally designated 400. In the illustrated embodiment, the method 400may be conducted prior to conducting a curing operation according to oneor more of the methods described herein, such as the methods 200, 300.The method 400 may include, in response to activation of a user input ofthe operator input 12 (e.g., a button), resetting or initializing anaccumulator or integrator of sensed energy delivered to a targetsurface. Steps 410 and 412. The controller 10 may then instruct theoptical drive circuitry 22 to power the light source 24 according to aninitial setting, such as a preselected source power level, therebystarting application of light. Step 414. The controller 10 may analyzethe optical sensor feedback signal provided from the optical feedbackcircuitry 26 to determine if the sensed reflected light is indicative ofthe curable material actually being targeted by the light applicationnumber 20. Steps 416, 418. As an example, the controller 10 may comparethe sensed light to a threshold, parameter, or parameter rangeassociated with the type of curable material being targeted to determinewhether the curable material is actually receiving light from the lightsource 24. If the sensed light is less than the threshold, or deviatesfrom the parameter range, the controller 10 may determine the curablematerial is improperly positioned relative to the light applicationnumber 20 such that a curing operation is unlikely to be effective.Based on this determination, the controller 10 may discontinue operationof the light source 24 or alert the operator of an issue via theoperator feedback circuitry 14, or a combination thereof. Step 420, 422.If the sensed light satisfies one or more criteria, such as beinggreater than a threshold, indicative of proper targeting of the curablematerial, the controller 10 may proceed with further steps in the curingoperation, including one or more steps described herein in connectionwith the methods 200, 300. The method 400 may transpire over the courseof several microseconds to substantially avoid application of lightenergy to surfaces other than that of a known or desired type of target.

In an addition to or as an alternative to one or more embodimentsdescribed herein, the curing light 100 may include an air path toconduct air or another gas toward or away from the target surface,thereby cooling the target surface or the surrounding area, or both. Asan example, as shown in broken lines in FIG. 2, the curing light 100 mayinclude a coolant system 150, including, for example, a pressurized airor vacuum source and an air path to conduct air from or to the targetsurface. In this way, air or another gas may be pushed or pulled,respectively via pressure or vacuum, past the target surface being curedto induce accelerated surface cooling at the target surface by virtue ofincreased air flow. The coolant system 150 may also utilize othercooling mechanism besides gas flow, such as directing water vapor orwater mist toward the target surface.

In one embodiment, the coolant system 150 may include a coupler,possibly disposed at or near a base of the curing instrument 100, thatallows a quick and reliable connection to a source of the pressurizedgas or vacuum. The coolant system may include an air channel locatedwithin the body of the curing instrument to direct and contain thepressurized or vacuum induced gas flow and guide it to or from the lightapplication member 20 of the curing instrument 100. The lightapplication member 20 may include a directional nozzle located at thetip of the light application member 20, and aimed in the direction ofthe illumination beam 64 to direct the gas flow either toward(pressurized gas) or away from (vacuum) the target surface being cured.The closed loop control of output from the light source 24 based on theoptical sensor feedback signal to manage total energy actually deliveredto the target surface may reduce the amount of heat energy delivered tothe target surface as compared to conventional curing operations inwhich a total amount of light energy delivered from a device ispreselected to be two to three times greater than that necessary inorder to compensate for operator induced variation in the amount oflight actually delivered. As a result, use of the coolant system 150 maybe substantially avoided. Optionally, however, the coolant system 150may be incorporated into the curing instrument 100 to offer theopportunity to operate at even higher levels of light intensity, therebyachieving a faster cure, without substantially allowing the resultanttemperature rise at the target surface to climb to levels above adetermined threshold.

In one embodiment, a method of manufacture of the curing instrument 100may include assembling the light application member 20 by aligning theoptical path 62 of the optical feedback sensor 28 with the optical path64 of the light source 24. The method may include energizing the opticalfeedback sensor 28 such that light is emitted from the light input 58.The light input 58 may be disposed a) in proximity to a lens 50 that ismounted to the light source 24 and b) within a void or area definedbetween the lens 50 and another lens 52. The light source 24 may beenergized to emit light at the same time as light is emitted from thelight input 58. The optical feedback sensor 28 may be rotated and movedsuch that the side-fire termination corresponding to the light input 58directs light along the optical path 62 within the optical path 64 ofthe light source 24. Once alignment between the optical path 62 in theoptical path 64 has been achieved, the optical feedback sensor 28 may beaffixed in place such that the light input 58 remains substantiallystable with respect to the lens 50. In one embodiment, a calibrationsensor system may detect the relative positions of the optical path 62of the light input 58 and the optical path 64 of the light source 24 tofacilitate alignment thereof. The light emitted from the light input 58during a calibration or alignment may be of a type different from thatemitted from the light source 24 to facilitate differentiating betweenthe optical path 62 and the optical path 64.

Directional terms, such as “vertical,” “horizontal,” “top,” “bottom,”“upper,” “lower,” “inner,” “inwardly,” “outer” and “outwardly,” are usedto assist in describing the disclosure based on the orientation of theembodiments shown in the illustrations. The use of directional termsshould not be interpreted to limit the present disclosure to anyspecific orientation(s).

The above description is that of current embodiments of the invention.Various alterations and changes can be made without departing from thespirit and broader aspects of the invention as defined in the appendedclaims, which are to be interpreted in accordance with the principles ofpatent law including the doctrine of equivalents. This disclosure ispresented for illustrative purposes and should not be interpreted as anexhaustive description of all embodiments of the invention or to limitthe scope of the claims to the specific elements illustrated ordescribed in connection with these embodiments. For example, and withoutlimitation, any individual element(s) of the described invention may bereplaced by alternative elements that provide substantially similarfunctionality or otherwise provide adequate operation. This includes,for example, presently known alternative elements, such as those thatmight be currently known to one skilled in the art, and alternativeelements that may be developed in the future, such as those that oneskilled in the art might, upon development, recognize as an alternative.Further, the disclosed embodiments include a plurality of features thatare described in concert and that might cooperatively provide acollection of benefits. The present invention is not limited to onlythose embodiments that include all of these features or that provide allof the stated benefits, except to the extent otherwise expressly setforth in the issued claims. Any reference to claim elements in thesingular, for example, using the articles “a,” “an,” “the” or “said,” isnot to be construed as limiting the element to the singular.

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:
 1. A dental curing instrument for curing a target, the target including a restorative material that is curable in response to application of light energy, the dental curing instrument comprising: a light source capable of outputting the light energy to cure the restorative material, the light source being controllable to vary the light energy being output; a light sensor for sensing a light energy characteristic; an optical feedback path operable coupled to the light sensor, the optical feedback path being disposed to channel light reflected back from the target to the light sensor, wherein the light sensor is configured to sense the light energy characteristic with respect to the light reflected back from the target; a controller operably coupled to the light sensor and the light source, the controller configured to vary, based on the light energy characteristic sensed by the light sensor, an operating characteristic of the light source to affect the light energy being output from the light source; wherein the controller is configured to iteratively calculate a total amount of energy delivered to the target based on the sensed light energy characteristic; and wherein the controller is configured to adjust the operating characteristic based on the calculated total amount of light energy.
 2. The dental curing instrument of claim 1 wherein the controller is configured to adjust the operating characteristic of the light source to counter degradation of the light source over a lifetime of the light source.
 3. The dental curing instrument of claim 1 wherein the light energy characteristic with respect to light reflected back from the target is a function of a material characteristic of the target, and wherein the total amount of energy delivered to the target is a based on the material characteristic of the target.
 4. The dental curing instrument according to claim 1 wherein the optical feedback path is aligned with an illumination beam of light of the light source being output from the dental curing instrument such that the optical feedback path is within the illumination beam.
 5. The dental curing instrument according to claim 4 wherein the optical feedback path is coaxially aligned with the illumination beam.
 6. The dental curing instrument according to claim 1 wherein the controller is configured to determine an amount of energy delivered to the target over a period of time, wherein the controller is configured to vary, based on the amount of energy determined to be delivered to the target over the period of time, the operating characteristic of the light source.
 7. The dental curing instrument of claim 6 wherein the controller is programmed to use the light energy characteristic sensed by the light sensor as a basis for determining a time integral of an optical intensity on the target, wherein the controller is programmed to compute, in real time, an actual total energy delivered to a surface of the target.
 8. The dental curing instrument of claim 7 wherein the actual total energy is expressed in terms of energy in Joules/cm2 equaling intensity in w/cm2*tsec, and wherein the controller uses the real time computation of Joules/cm2 as a basis for controlling the light source to control an amount of energy delivered by managing a time of active exposure.
 9. The dental curing instrument of claim 1 wherein the total amount of energy delivered to the target is displayed to the user, and wherein the total amount of energy displayed to the user is expressed in Joules/cm2.
 10. The dental curing instrument according to claim 1 wherein the optical feedback path and the light sensor form isolated optical feedback to the controller, wherein the controller is configured to assess, in real time, an actual light intensity (mW/cm2) delivered to a surface of the target, wherein the assessment is independent from operator induced variation caused by at least one of distance or angle of presentation of the dental curing instrument with respect to the target.
 11. The dental curing instrument according to claim 1 wherein the light sensor provides a real-time intensity optical sensor feedback signal, wherein the controller, based on the real-time intensity optical sensor feedback signal, produces corrective adjustments by controlling a light source intensity of the light source, whereby the controller stabilizes an actual light intensity delivered to a surface of the target.
 12. The dental curing instrument of claim 1 wherein the optical feedback path is shared with a light delivery path through which the light source outputs energy to the target, wherein the controller is programmed to differentially and ratiometrically assess the light energy output from the light source and the light reflected back from the target, wherein signals indicative of the light energy output and the light reflected back are obtained from within the shared light delivery path.
 13. The dental curing instrument of claim 1 comprising a user interface operable to facilitate setting an operational parameter of the dental curing instrument.
 14. The dental curing instrument of claim 13 wherein the user interface is operable to facilitate setting the operational parameter based on a manufacturer prescribed setting for a material selected by a user for use as the restorative material.
 15. The dental curing instrument of claim 1 comprising a gas channel coupled to a gas nozzle that directs gas over the target to affect a temperature of the target.
 16. A method of operating a curing instrument to conduct a curing operation of a light-curable material, the method comprising: generating light energy from a light source; directing the light energy, from a light application member of the curing instrument, toward a target surface associated with the light-curable material; generating an optical sensor feedback signal based on sensed light reflected from the target surface; adjusting, based on the optical sensor feedback signal, output of the light energy from the light source to affect the light energy being output from the light source; iteratively calculating a total amount of energy delivered to the light-curable material based on the optical sensor feedback signal; and adjusting an operating characteristic of the light source based on the calculated total amount of light energy.
 17. The method of claim 16 comprising determining an amount of light energy delivered to the light-curable material over a period of time, and varying the output of the light energy from the light source based on the amount of light energy determined to be delivered to the light-curable material over the period of time.
 18. The method of claim 17 comprising: delivering light energy to the target surface according to a curing profile; determining whether the amount of light energy calculated to be delivered for the amount of time is substantially similar to an expected amount of light energy according to the curing profile for the amount of time; and adjusting the output of light energy from the light source based on a determination that the calculated total amount of light energy is different from the expected amount of light energy.
 19. The method of claim 16 comprising sensing via an optical sensor light reflected from the target surface, wherein the light reflected from the target surface is indicative of an amount of light energy actually delivered from the light source to the target surface.
 20. The method of claim 16 comprising supplying a power signal to the light source in order to generate the light energy, and wherein said adjusting the output of the light energy from the light source includes varying a characteristic of the power signal supplied to the light source.
 21. The method of claim 16 comprising setting an operational parameter of the curing instrument based on user input.
 22. The method of claim 21 wherein the operational parameter is based on a manufacturer prescribed setting for a material selected by a user for use as the light-curable material.
 23. The method of claim 16 comprising adjusting a supply of power to the light source to counter degradation of the light source over a lifetime of the light source.
 24. The method of claim 16 wherein the optical sensor feedback signal that is based on sensed light reflected back from the target surface is a function of a material characteristic of the light-curable material, and wherein the total amount of energy delivered to the light-curable material is a based on the material characteristic of the light-curable material. 